This invention relates to the long term stabilization of an enzyme contained in an aqueous composition by an alkanolamine and an organic or inorganic acid.
The desirability of using proteolytic and alpha amylolytic enzymes in cleaning compositions is well known. These enzymes are useful for their ability to reduce macromolecules such as proteins and starches into smaller molecules so that they can be readily washed away by detergents and/or water. Specifically, the proteolytic enzymes are useful in breaking down proteins and the alpha amylolytic enzymes are useful in breaking down carbohydrates. Detergent compositions containing these enzymes have a wide variety of uses in that they care capable of removing proteinaceous and starchy stains such as egg stains, blood stains, gravy stains and the like.
Detergent compositions containing enzymes have been commercially available in dry powdered form. However, there are inherent problems with these compositions. First, they must be stored in such a way as to be protected from humidity and high heat to insure enzyme stability. Second, these dry powdered compositions are not well suited for several useful applications such as spot cleaners, laundry pre-soaks and pre-spotters which require direct application to the stained surface. For these and other applications it is desirable to have an aqueous enzyme composition. Economic as well as processing considerations necessitate the use of water in liquid enzyme compositions. However, there is an inherent problem in adding an enzyme to an aqueous medium in that enzymes are rapidly denatured in water resulting in a loss of enzyme activity.
In order to have an aqueous enzyme composition which is suitable for the uses described above, the enzyme must be stabilized so that it can retain its activity for long periods of time.
Attempts have been made to stabilize enzymes contained in water based compositions.
U.S. Pat. No. 3,296,094 to Cayle utilizes a partially hydrolyzed and solubilized collagen, and glycerol to stabilize an aqueous proteolytic enzyme composition. The amount of glycerol required for stabilization in this composition is between 35% to 60% by weight of the total composition. The large quantities of glycerol required render this composition relatively expensive.
U.S. Pat. No. 3,557,002 to McCarty utilizes a monohydroxy alcohol or an alkoxy alcohol to stabilize a proteolytic enzyme. Although the amount of alcohol used in this composition is less than that used in Cayle the residual activity of the enzyme of this composition decreases after long periods of storage at relatively high temperatures.
It is an object of this invention to provide stabilized aqueous enzyme compositions which are capable of maintaining enzyme activity for long periods of time.
It is a further object of this invention to provide stable aqueous enzyme compositions by using small amounts of relatively inexpensive stabilizing agents.